Ms. Bartholet, a public interest professor and Faculty Director of Harvard Law School’s Child Advocacy Program (CAP), warned writer Erin O’Donnell of “extreme religious ideologues” among roughly 2 million U.S. homeschoolers.

“Surveys of homeschoolers show that a majority of such families (by some estimates, up to 90 percent) are driven by conservative Christian beliefs, and seek to remove their children from mainstream culture,” Ms. O’Donnell wrote. “Bartholet notes that some of these parents are ‘extreme religious ideologues’ who question science and promote female subservience and white supremacy.”

The professor also warned that homeschooling — an “unregulated regime” — may allow parents too much time with their children.

“The issue is, do we think that parents should have 24/7, essentially authoritarian control over their children from ages zero to 18? I think that’s dangerous,” Ms. Bartholet said. “I think it’s always dangerous to put powerful people in charge of the powerless and to give the powerful ones total authority.”

Ms. Bartholet called for more stringent laws for homeschoolers despite populations that do an adequate job educating their children.

“I think an overwhelming majority of legislators and American people, if they looked at the situation, would conclude that something ought to be done,” the professor said.

The conservative website National Review bristled at the professor’s premise.

“Bartholet is pretty open about her program, which has less to do with ensuring equal educational opportunity across socioeconomic groups (ho, ho!) and more to do with extending the surveillance state, lest unsupervised proles make child-rearing decisions at odds with the priorities Bartholet would prefer to see enforced,” Kevin D. Williamson wrote Tuesday.

“The conception of the public schools as a coercive and homogenizing moral force is fundamental to the mandatory-education project — our very first public-education law (known by the wonderfully evocative title ‘Old Deluder Satan Act’) was explicitly anti-Catholic in its intent, as were many of the public-education laws (Blaine amendments, etc.),” he continued. “Like our Puritan forebears, contemporary progressives believe that what keeps the infidels from the One True Faith is mostly ignorance, which can be cured through coercive indoctrination.”